Fabrication of Dual‐Functional MXene@NiCo 2 S 4 Composites with Enhanced Nonlinear Optical and Electrochemical Properties

The design and synthesis of multifunctional nanomaterials have attracted considerable attention for expanding the range of practical applications. Herein, a metal-organic framework (MOFs)-derived NiCo₂S₄ attached to MXene is rationally designed and constructed for an optical limiter and supercapacitor. The MOF-derived NiCo₂S₄ enhances the tendency of hydroxyl groups on the MXene surface to attract metal ions, resulting in the formation of sulfur vacancies. Moreover, MXene offers a high specific surface area to facilitate the rapid complexation of charge carriers. The resultant MXene@NiCo₂S₄ (MX@NCS) exhibits markedly enhanced nonlinear optical (NLO) and electrochemical properties through synergistic interactions between the components. The NLO properties can be further optimized by adjusting the amount of MX@NCS powder dispersed in methyl methacrylate (MX@NCS)_2-6/PMMA) by using the Z-scan technique. Specifically, the (MX@NCS)₄/PMMA exhibits the strongest reverse saturable absorption (RSA) and self-defocusing effects at 100 µJ with β = 3.87 × 10² cm·GW^-1 and γ = -5.94 × 10^-4 cm²·GW^-1. Concurrently, the constructed supercapacitor shows a superior energy density of 51.21 Wh·kg^-1 at a power density of 863.65 W·kg^-1. Notably, the present study indicates a novel strategy to explore the application of materials in the development of efficient optical limiter and supercapacitor technologies.